Circuit breakers, both single and multi-phase circuit breakers, typically include a lever or other device for manually operating the circuit breaker. Frequently, it is desirable that the lever be operated through the use of a mechanical interface, such as a direct mount rotary handle operating mechanism having a handle that may be manually operated, wherein the handle mechanism is of the type that is directly mounted to the circuit breaker.
In operation, the handle mechanism moves the circuit breaker lever to its various operative positions. This includes an “ON” position, an “OFF” position and a “RESET” position. In some instances, it is necessary to lock the handle mechanism in the OFF position so as to safeguard personnel working on associated equipment. However, when the electrical contacts of the circuit breaker have become welded closed, usually as a result of a short circuit condition, locking the handle mechanism in an OFF position would create a dangerous and inappropriate condition since a user would believe that the circuit breaker is in the OFF (electrical contacts open) condition, when in fact the electrical contacts are welded closed.
Conventional handle mechanisms include a locking portion that will not enable locking of the handle when the contacts are welded together. This is commonly referred to as “Suitable for Isolation” or “Positive OFF”. In addition, the handle will return to indicate the ON position when the handle is released. These are safety features that indicate to the user that the contacts are welded and that substantially reduce the likelihood that others working on the equipment would mistakenly believe that the contacts are open.
However, conventional handle mechanisms rely on the proper positioning of the handle as a way of ensuring that it will not lock during Positive OFF. The disadvantage of such mechanisms is, that with wear, the position of the handle mechanism approaches the locked position. Further, such mechanisms rely on the force limits set by standard specifications, such as those set by the International Electrotechnical Commission (IEC), in order to ensure the handle cannot be locked.
U.S. Pat. No. 6,969,813 (Michael Troy Winslett, et al.), the disclosure of which is incorporated herein by reference, discloses a direct mount rotary handle operating mechanism for operating a circuit breaker having electrical contacts. The handle mechanism includes a driver coupled to the circuit breaker and a handle having a socket for receiving the driver. The socket is configured to allow the handle to rotate relative to the driver. The handle further includes a movable locking pin. A lock latch is associated with the driver, wherein the lock latch includes a flange portion. When the electrical contacts of the circuit breaker are welded closed and a torque is applied to the handle, the handle rotates to a position in which the pin is blocked from being inserted into the locking hole by the flange portion thereby preventing the handle from being locked in an OFF position when the contacts are welded together.
U.S. Pat. No. 7,368,675 (Hideki Ishido, et al.), the disclosure of which is incorporated herein by reference, discloses an external operation handle device is used for a circuit breaker for switching a locker handle to ON and OFF positions. The handle device includes a main body casing for the circuit breaker, a mount base held on the main body casing, a rotary handle grip mounted on the mount base for turning the locker handle to the ON and OFF positions and having a connecting shaft, and an assist mechanism for moving the handle grip to a TRIP indication position upon tripping operation of the circuit breaker. The assist mechanism is interposed between the mount base and the handle grip, and includes a cam with a cam face, fixed on the mount base, a cam follower linking with the handle grip slidably along an axial direction and opposing the cam face of the cam, and an urging spring for pushing the cam follower against the cam face.
U.S. Pat. No. 7,399,934 (Takeshi Emura, et al.), the disclosure of which is incorporated herein by reference, discloses an external operation handle device for a circuit breaker includes a rotary handle equipped with a handle lock lever, a drive mechanism linking the rotary handle and the locker handle of the circuit breaker, and a door lock lever for interlocking between the rotary handle and a door of the board. By operating the rotary handle, the circuit breaker can be turned to an ON or OFF position, and the door is unlocked at an OPEN position. The handle lock lever is slidably disposed on the rotary handle to be anchored and held at a pulled out position in a condition where the rotary handle at the OPEN position unlocks the door of the board, and the door lock lever linked to the rotary handle is cramped and held at the unlock position in a condition where the rotary handle is at the OPEN position.
Furthermore, the National Fire Protection Association (NFPA) 79 standard calls for a means to operate a breaker's handle at all time. And this becomes an issue, especially, when the electrical enclosure door is either closed or is opened.
Thus, a need exists for a shaft support bracket for an extended drive-plate deliberate action rotary handle.
This invention overcomes the problems of the prior art and provides a shaft support bracket for an extended drive-plate deliberate action rotary handle, that engages a component, such as, a circuit breaker, only upon a deliberate action by an operator.